feat(checklist): Add Modified Transaction Validity Constraint (#1988)

* feat(checklist): Add `Modified Transaction Validity Constraint`

* fix: tox

* fix: review comments

Author: marioevz

docs/writing_tests/checklist_templates/eip_testing_checklist_template.md

@@ -1165,3 +1165,42 @@ Verify tests in `tests/cancun/eip4844_blobs` were correctly and automatically up
 ### Framework Changes
 
 - Increment `max_request_type` in the fork where the EIP is introduced in `src/ethereum_test_forks/forks/forks.py` to the new maximum request type number after the EIP is activated.
+
+## New Transaction-Validity Constraint
+
+### Test Vectors
+
+#### Fork transition
+
+| ID                                        | Description                                                                                                                               | Status | Tests |
+| ----------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------- | ------ | ----- |
+| `new_transaction_validity_constraint/test/fork_transition/accepted_before_fork` | Verify that a block before the activation fork is accepted even when the new constraint is not met. |        |       |
+| `new_transaction_validity_constraint/test/fork_transition/accepted_after_fork` | Verify that a block after the activation fork is accepted when the new validity constraint is met. |        |       |
+| `new_transaction_validity_constraint/test/fork_transition/rejected_after_fork` | Verify that a block after the activation fork is rejected when the new validity constraint is not met. |        |       |
+
+Note: All test cases must use off-by-one values to ensure proper boundary condition verification.
+
+### Framework Changes
+
+- Introduce the validity constraint as a fork method that returns:
+    - `None` for forks before its activation.
+    - A non-`None` value starting from the fork where the constraint becomes active.
+
+## Modified Transaction-Validity Constraint
+
+### Test Vectors
+
+#### Fork transition
+
+| ID                                        | Description                                                                                                                               | Status | Tests |
+| ----------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------- | ------ | ----- |
+| `modified_transaction_validity_constraint/test/fork_transition/accepted_before_fork` | Verify that a block before the activation fork is accepted when the existing constraint is met and, ideally, the new constraint is not met. |        |       |
+| `modified_transaction_validity_constraint/test/fork_transition/rejected_before_fork` | Verify that a block before the activation fork is rejected when the existing constraint is not met and, ideally, the new constraint is met. |        |       |
+| `modified_transaction_validity_constraint/test/fork_transition/accepted_after_fork` | Verify that a block after the activation fork is accepted when the new validity constraint is met. |        |       |
+| `modified_transaction_validity_constraint/test/fork_transition/rejected_after_fork` | Verify that a block after the activation fork is rejected when the new validity constraint is not met. |        |       |
+
+Note: All test cases must use off-by-one values to ensure proper boundary condition verification.
+
+### Framework Changes
+
+- Update the validity constraint as a fork method that returns the updated value starting from the fork where the constraint changes.

src/ethereum_test_checklists/eip_checklist.py

@@ -1675,3 +1675,77 @@ class Update(ChecklistItem):
                     """Update cross-request tests."""
 
                     pass
+
+    class NewTransactionValidityConstraint(ChecklistItem):
+        """New transaction validity constraint checklist items."""
+
+        class Test(ChecklistItem):
+            """Test vectors for the new validity constraint."""
+
+            class ForkTransition(ChecklistItem):
+                """Tests for the new transaction validity constraint on fork boundary."""
+
+                class AcceptedBeforeFork(ChecklistItem):
+                    """
+                    Verify that a block before the activation fork is accepted even when the new
+                    constraint is not met.
+                    """
+
+                    pass
+
+                class AcceptedAfterFork(ChecklistItem):
+                    """
+                    Verify that a block after the activation fork is accepted when the new
+                    validity constraint is met.
+                    """
+
+                    pass
+
+                class RejectedAfterFork(ChecklistItem):
+                    """
+                    Verify that a block after the activation fork is rejected when the new
+                    validity constraint is not met.
+                    """
+
+                    pass
+
+    class ModifiedTransactionValidityConstraint(ChecklistItem):
+        """Modified transaction validity constraint checklist items."""
+
+        class Test(ChecklistItem):
+            """Test vectors for the modified validity constraint."""
+
+            class ForkTransition(ChecklistItem):
+                """Tests for the modified transaction validity constraint on fork boundary."""
+
+                class AcceptedBeforeFork(ChecklistItem):
+                    """
+                    Verify that a block before the activation fork is accepted when the existing
+                    constraint is met and, ideally, the new constraint is not met.
+                    """
+
+                    pass
+
+                class RejectedBeforeFork(ChecklistItem):
+                    """
+                    Verify that a block before the activation fork is rejected when the existing
+                    constraint is not met and, ideally, the new constraint is met.
+                    """
+
+                    pass
+
+                class AcceptedAfterFork(ChecklistItem):
+                    """
+                    Verify that a block after the activation fork is accepted when the new
+                    validity constraint is met.
+                    """
+
+                    pass
+
+                class RejectedAfterFork(ChecklistItem):
+                    """
+                    Verify that a block after the activation fork is rejected when the new
+                    validity constraint is not met.
+                    """
+
+                    pass